Wood-walled log structure having durable butt joints and method of manufacturing the same

ABSTRACT

For use in constructing a log structure, a log and a kit of logs, and a method of manufacturing the same. In one embodiment, the log includes: (1) a body having a first end and a second end, (2) an integral tongue projecting from the first end and (3) a groove located in the second end.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application Ser. No. 61/139,547, filed by White on Dec. 19, 2008, entitled “LocLog,” commonly owned with this application and incorporated herein by reference.

TECHNICAL FIELD

This application is directed, in general, to wood-walled log structures, such as log homes, and, more specifically, to a wood-walled log structure having durable butt joints and a method of manufacturing such joints and such log structure.

BACKGROUND

Log homes are currently experiencing a resurgence in popularity. Factors contributing to the appeal for this type of building construction include the simplicity of their design, low maintenance and durability, and economy of construction.

The log cabins built by the early settlers used logs, either rounded or hand hewn into a squared configuration, and stacked one above another with a joint at the corners of the building. The spaces between adjacent logs were filled with a chinking material (e.g., Portland cement, sand and lime), usually clay or mud.

The log buildings of today are much more finished and sophisticated than those of the early settlers. Such buildings may use whole logs, logs that have a flat surface formed thereon to yield a flat interior wall or logs that are built from multiple plies of wood planks affixed together, typically by means of glue.

SUMMARY

One aspect provides a log structure. In one embodiment, the log includes: (1) a body having a first end and a second end, (2) an integral tongue projecting from the first end and (3) a groove located in the second end.

Another aspect provides a kit for constructing a log structure. In one embodiment, the kit includes a plurality of logs, at least some of the plurality of logs each having: (1) a body having a first end and a second end, (2) an integral tongue projecting from the first end and (3) a groove located in the second end.

Yet another aspect provides a method of manufacturing a kit for use in constructing a log structure. In one embodiment, the method includes forming a plurality of logs, at least some of the forming of the logs including: (1) forming a body having a first end and a second end, (2) forming an integral tongue that projects from the first end and (3) forming a groove located in the second end.

BRIEF DESCRIPTION

Reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

FIG. 1 is an isometric view of a portion of a log structure;

FIG. 2 is a schematic elevational view of a portion of a wall of the structure of FIG. 1;

FIG. 3 is a collection of topside, leftside and rightside plan views and an elevational view of a first embodiment of a log having a durable butt joint constructed according to the principles of the invention;

FIG. 4 is a collection of topside, leftside and rightside plan views and an elevational view of a second embodiment of a log having a durable butt joint constructed according to the principles of the invention;

FIG. 5 is a collection of topside, leftside and rightside plan views and an elevational view of a third embodiment of a log having a durable butt joint constructed according to the principles of the invention; and

FIG. 6 is a flow diagram of one embodiment of a method of manufacturing a log having a durable butt joint carried out according to the principles of the invention.

DETAILED DESCRIPTION

Various techniques have been used in the past to join adjacent ends of logs. The most primitive techniques involved squaring off the ends of the logs and simply butting the squared-off ends together. On a given log wall, the joints were offset from one course of logs to the next, such that joints on adjacent courses did not overlap. While the joints themselves had little if any strength, the adjacent courses provided strength; and the overall wall was reasonable strong. Later techniques employed rods to join the courses, allowing adjacent courses to strengthen the wall to an even greater extent. The most recent techniques involve cutting a groove in the ends of the logs and employing a separate member to fit in adjoining grooves in the nature of a biscuit. This technique has enjoyed reasonable success, and is employed in many modern log structures being sold and built today.

Many log structures are now manufactured at a factory, shipped to a building site as a kit and assembled on-site by a contractor or an owner. As successful as the above-described techniques have been, the above-described recent technique relies on the contractor or owner to supply a piece of wood or other material to use as the biscuit. This has proven problematic. Some contractors use leftover wood flooring; others use whatever excess wood or material may be lying around the jobsite. The grain of the biscuit may be oriented in any direction relative to the logs it joins. Therefore, the strength of the biscuit is likely to be reduced when its grain is misaligned with respect to the grain of the adjacent logs (which runs lengthwise along whole logs and at least predominantly lengthwise along logs made of separate plies of planks). It is realized herein that the recent technique is deficient in that the strength of the joint relies on the competence and care of the contractor or owner. Stated another way, it is realized herein that much of the making of the butt joint lies outside of the manufacturer's control, potentially compromising the quality that the manufacturer has designed into other aspects of the structure. What is therefore desired is to bring the joint under the control of the manufacturer, such that the overall quality and strength of the resulting structure improves.

To address these realizations, various embodiments of a wood-walled log structure having durable butt joints will now be described. In general, the butt joints employ a tongue and groove to join adjacent logs. The tongue is integral with one of the logs. In general, “integral” means manufactured into, and only destructively separable from, the remainder of the log (the log body) by, for example, cutting it off or ripping it out. The meaning of “integral” is best understood by referring to the various embodiments described herein. In some embodiments, the tongue is part of the same tree as the rest of the log and has never been separated from the log body. Instead, the tongue is formed by removing portions of the log around the tongue. In other embodiments, the log is made of separate plies of planks, and the tongue is made by allowing one or more of the plies of planks to extend from the end of the log. Since the plies of planks are glued or otherwise fixed together, usually over the whole length of the body, the tongue is integral with the log.

It is believed that making the tongue integral with the log guarantees that it will be of a desired strength. It is further believed that making the tongue integral with the log substantially decreases, and probably removes, the risk that a contractor or owner will use substandard or poorly oriented wood to bridge the ends of adjacent logs. It is yet further believed that a log structure perhaps containing many dozens of such butt joints will be substantially stronger and perceived as being of substantially higher quality than a structure having conventional butt joints.

FIG. 1 is an isometric view of a portion of a log structure, generally designated 100. The log structure 100 may be a residential structure, such as a cabin or home, a commercial structure, such as a store or restaurant, or a utility structure, such as a shed or an outbuilding.

The structure 100 includes a wall 110. The wall 110 includes at least two logs that are typically oriented generally horizontally over one another as FIG. 1 shows. In one embodiment, the logs are generally circular in cross-section. In another embodiment, the logs are generally partially circular in cross-section, but also have a generally flat surface that is typically oriented toward an interior of the structure. This allows the wall 110 to have a flat interior profile or be attached to a conventional building frame such as may be made of milled lumber (not shown), such as colloquially-named “2 by 4”s.

The wall 110 is shown as having an opening therein to accept, e.g., a window 120 or a door (not shown). Various known and conventional techniques may be used to provide openings in a wall to accommodate one or more windows or doors as may be desired for a particular structure.

The structure 100 has walls (not shown) in addition to the wall 110. The other walls are attached to the wall 110 at opposing ends thereof. Various known and conventional techniques may be used to join walls together durably, perhaps to result in an enclosed structure.

The structure also has a roof 130 positioned over the walls in the illustrated embodiment. The roof 130 is designed to provide further integrity to the structure 110 and also shelter the interior of the structure from sun and rain or other falling matter.

FIG. 2 is a schematic elevational view of a portion of the wall 110. The portion illustrated in FIG. 2 includes three courses of logs. An upper course includes logs 210, 220. A middle course includes logs 230, 240. A lower course includes logs 250, 260. Various conventional methods may be used to join the courses of logs 210, 220, 230, 240, 250, 260 together. For example, one embodiment employs a chinking material not only to cause the courses of logs 210, 220, 230, 240, 250, 260 to resist displacement but to decrease the flow of water or air between the courses. Another embodiment calls for flat, concave or channeled surfaces to be formed on adjacent surfaces of the courses of logs 210, 220, 230, 240, 250, 260 to increase the amount of contact surface or cause them to resist displacement by taking advantage of gravity, friction or positive interlocking. A chinking material may be employed in addition to the flat, concave or channeled surfaces, perhaps to provide additional resistance to displacement of the courses and decrease the flow of water or air therebetween. Yet another embodiment employs fasteners such as nails, screws or rods that span multiple courses to hold them together positively. Again, a chinking material may be employed to provide additional resistance to displacement of the courses and decrease the flow of water or air therebetween. Still another embodiment affixes the courses to an adjacent structure, such as a conventional building frame made of milled lumber, using nails, screws, rods or hangers. The courses may thus be regarded as a log veneer.

FIG. 3 is a collection of topside, leftside and rightside plan views and an elevational view of a first embodiment of a log having a durable butt joint constructed according to the principles of the invention. As FIG. 3 shows, a body 310 of the log has a generally circular cross-section.

The body 310 has a first end 320 having an integral tongue 330 projecting therefrom. In the embodiment of FIG. 3, the tongue 330 is formed by removing part of the first end 320 of the body 310. That part is not referenced, because it is missing from FIG. 3; however it lies on either side of the tongue 330. In a more specific embodiment, the tongue 330 is formed by sawing to remove the part of the one end. In one embodiment, the tongue 330 is formed such that the tongue 330 is placed in a vertical orientation when the log is installed as part of a structure. This may be done by defining other features on the body 310 that allows it to fit with logs on adjacent courses (not shown) when correctly oriented. In an alternative embodiment, the tongue 330 is formed such that it is placed at a nonzero angle with respect to the vertical when the log is installed as part of a structure. The tongue 330 may, for example, be oriented at 45° with respect to the vertical. In the embodiment of FIG. 3, the tongue 330 has a generally rectangular cross-section over its length. In an alternative embodiment, the tongue 330 has other than a generally rectangular cross-section over at least part of its length. The latter embodiment accommodates one or more frictional or positive engagement features, such as ramps or ledges (not shown), that tend to retain the tongue 330 within a groove once inserted.

FIG. 3 illustrates the tongue 330 as spanning the full diameter of the body 310. This may be advantageous in some applications, but is not necessary. In an alternative embodiment, the tongue 330 spans only part of the diameter of the body 310. In another embodiment, the tongue 330 is offset from the center of the body 310, perhaps to allow the log to be rotationally keyed to its adjacent logs.

The body 310 also has a second end 340, illustrated as being distal from the first end 320 and having a groove 350 recessed therein. In the embodiment of FIG. 3, the groove 350 is formed by forming a slot in the second end 340 of the body 310. In a more specific embodiment, the groove 350 is formed by sawing. In one embodiment, the groove 350 is formed such that the groove 350 is placed in a vertical orientation when the log is installed as part of a structure, allowing it to mate with a corresponding vertically-oriented tongue on an adjacent log (not shown). As with the tongue 330, this may be done by defining other features on the body 310 that allows it to fit with logs on adjacent courses (not shown) when correctly oriented. In an alternative embodiment, the groove 350 is formed such that it is placed at a nonzero angle with respect to the vertical when the log is installed as part of a structure. The groove 350 may, for example, be oriented at 45° with respect to the vertical. In the embodiment of FIG. 3, the groove 350 has a generally rectangular cross-section over its length. In an alternative embodiment, the groove 350 has other than a generally rectangular cross-section over at least part of its length. The latter embodiment accommodates one or more frictional or positive engagement features, such as ramps or ledges (not shown), that tend to retain a tongue within the groove 350 once inserted.

FIG. 3 illustrates the groove 350 as spanning the full diameter of the body 310. This may be advantageous in some embodiment, the groove 350 spans only part of the diameter of the body 310. In another embodiment, the groove 350 is offset from the center of the body 310, perhaps to allow the log to be rotationally keyed to its adjacent logs.

FIG. 4 is a collection of topside, leftside and rightside plan views and an elevational view of a second embodiment of a log having a durable butt joint constructed according to the principles of the invention. As FIG. 4 shows, the body 310 has a generally partially circular cross-section and a generally flat surface 410. The generally flat surface 410 is typically oriented toward an interior of the structure, allowing the wall to have a flat interior profile or be attached to a conventional building frame such as may be made of milled lumber. In the embodiment of FIG. 4, the tongue 330 and the groove 350 are generally parallel with the generally flat surface 410. In an alternative embodiment, the tongue 330 and the groove 350 are oriented at a nonzero angle with respect to the generally flat surface 410.

FIG. 5 is a collection of topside, leftside and rightside plan views and an elevational view of a third embodiment of a log having a durable butt joint constructed according to the principles of the invention. In the embodiment of FIG. 5, plies of planks (not separately referenced) are affixed together to form a laminated log, and the laminated log is shaped to have a generally partially circular cross-section and a generally flat surface. Although the planks are not separately referenced, it is apparent in FIG. 5 that the tongue 330 is formed by offsetting one or more plies of planks from the remainder of the plies of planks such that the one or more plies of planks protrude from the one end of the log to form the tongue 330. In the specific embodiment of FIG. 5, two plies of planks are offset from the remainder of the plies of planks. However, those skilled in the art should understand that other numbers of planks fall within the scope of the invention. Also in the embodiment of FIG. 5, the offset of the same plies of planks also forms the groove 350. This is advantageous in that the plies of planks are the same general length over the log. However, this need not be the case.

In another embodiment that is not illustrated, plies of planks are affixed together to form a laminated log like that of FIG. 5, but the laminated log is shaped to have a generally circular cross-section like that of FIG. 2 and therefore lacks the generally flat surface 410 thereof.

Various embodiments of a method of manufacturing such joints and such log structure will now be described. FIG. 6 is a flow diagram of one embodiment of a method of manufacturing a log having a durable butt joint carried out according to the principles of the invention. The method begins in a start step 610.

In a step 620, the body of the log is formed. In one embodiment, a raw log is shaped to have a generally circular cross-section. In another embodiment, a raw log is shaped to have a generally partially circular cross-section and a generally flat surface. In yet another embodiment, plies of planks are affixed together to form a laminated log, and the laminated log is shaped to have a generally circular cross-section. In still another embodiment, plies of planks are affixed together to form a laminated log, and the laminated log is shaped to have a generally partially circular cross-section and a generally flat surface.

In a step 630, a tongue is formed on one end of the log. In one embodiment, the tongue is formed by removing part of one end of the log. In a more specific embodiment, the tongue is formed by sawing to remove the part of the one end. In another embodiment, the tongue is formed by offsetting one or more plies of planks from the remainder of the plies of planks such that the one or more plies of planks protrude from the one end of the log to form a tongue. In one embodiment, the tongue is formed such that it is placed in a vertical orientation when the log is installed as part of a structure. In an alternative embodiment, the tongue is formed such that it is placed at a nonzero angle with respect to the vertical when the log is installed as part of a structure. In one embodiment, the tongue has a generally rectangular cross-section over its length. In an alternative embodiment, the tongue has other than a generally rectangular cross-section over at least part of its length. The latter embodiment accommodates one or more frictional or positive engagement features, such as ramps or ledges, that tend to retain the tongue within a groove once inserted.

In a step 640, a groove is formed on one end of the log. In one embodiment, the groove is formed on an end opposite that on which the tongue is formed in the step 630. In one embodiment, the groove is formed by removing part of one end of the log. In a more specific embodiment, the groove is formed by sawing to remove the part of the one end. In another embodiment, the groove is formed by offsetting one or more plies of planks from the remainder of the plies of planks such that the one or more plies of planks recede into the one end of the log to form a groove. In one embodiment, the groove is formed such that it is placed in a vertical orientation when the log is installed as part of a structure. In an alternative embodiment, the groove is formed such that it is placed at a nonzero angle with respect to the vertical when the log is installed as part of a structure. In one embodiment, the groove has a rectangular cross-section over its length. In an alternative embodiment, the groove has other than a rectangular cross-section over at least part of its length. The latter embodiment accommodates one or more frictional or positive engagement features, such as ramps or ledges, that tend to retain a tongue within the groove once inserted. In one specific embodiment, the one or more frictional or positive engagement features formed in the tongue correspond to or cooperate with one or more frictional or positive engagement features formed in the groove such that the tongues and grooves of adjacent logs in a structure lock into one another as the structure is assembled.

The steps 620, 630 and 640 may be repeated as necessary to yield a plurality of manufactured logs, for example to produce at least part of a log structure kit for later assembly, perhaps by a purchaser of the kit. The method ends in an end step 640.

Those skilled in the art to which this application relates will appreciate that other and further additions, deletions, substitutions and modifications may be made to the described embodiments. 

1. For use in constructing a log structure, a log, comprising: a body having a first end and a second end; an integral tongue projecting from said first end; and a groove located in said second end.
 2. The log as recited in claim 1 wherein said body has a generally circular cross-section.
 3. The log as recited in claim 1 wherein said body has a generally partially circular cross-section and a generally flat surface.
 4. The log as recited in claim 1 wherein said body comprises plies of planks affixed together, at least one of said planks offset from other of said planks to form said tongue.
 5. The log as recited in claim 4 wherein said offset of said at least one of said planks also forms said groove.
 6. The log as recited in claim 1 wherein said tongue is formed such that said tongue is placed in a vertical orientation when said log is installed as part of said log structure.
 7. The log as recited in claim 1 wherein said tongue has a generally rectangular cross-section over a length thereof.
 8. A kit for constructing a log structure, comprising: a plurality of logs, at least some of said plurality of logs each including: a body having a first end and a second end, an integral tongue projecting from said first end, and a groove located in said second end.
 9. The kit as recited in claim 8 wherein said body has a generally circular cross-section.
 10. The kit as recited in claim 8 wherein said body has a generally partially circular cross-section and a generally flat surface.
 11. The kit as recited in claim 8 wherein said body comprises plies of planks affixed together, at least one of said planks offset from other of said planks to form said tongue.
 12. The kit as recited in claim 11 wherein said offset of said at least one of said planks also forms said groove.
 13. The kit as recited in claim 8 wherein said tongue is formed such that said tongue is placed in a vertical orientation when said log is installed as part of said log structure.
 14. The kit as recited in claim 8 wherein said tongue has a generally rectangular cross-section over a length thereof.
 15. A method of manufacturing a kit for use in constructing a log structure, comprising: forming a plurality of logs, at least some of said forming of said logs including: forming a body having a first end and a second end, forming an integral tongue that projects from said first end, and forming a groove located in said second end.
 16. The method as recited in claim 15 wherein said body has a generally circular cross-section.
 17. The method as recited in claim 15 wherein said body has a generally partially circular cross-section and a generally flat surface.
 18. The method as recited in claim 15 wherein said forming said body comprises affixing plies of planks together and said forming said tongue comprises offsetting at least one of said planks from other of said planks.
 19. The method as recited in claim 18 wherein said offsetting said at least one of said planks also carries out said forming said groove.
 20. The method as recited in claim 15 wherein said tongue is placed in a vertical orientation when said log is installed as part of said log structure. 